Earthquakes and volcanoes

In this section we’re going to focus on earthquakes and volcanoes, both of which are related to tectonic plates.

Volcanic eruptions are caused by molten rock from the inner Earth layers erupting out of the crust due to the movement of tectonic plates. The slopes of some volcanoes bulge before they erupt.

We are therefore able to measure the angle of a volcano as a way of predicting when they may happen, which can save many lives. Despite this it is still difficult to predict volcanic eruptions and earthquakes.

However, we still can’t know exactly when tectonic plates will slip past each other. Tectonic plates are formed from parts of the upper mantle and crust and move very slowly due to convection currents.

It is thought that volcanoes released carbon dioxide, water vapour and nitrogen gas into the early atmosphere. The water vapour then condenses to form the ocean. The early atmosphere eventually stabilised and was made up mainly of carbon dioxide with small amounts of water vapour, methane and ammonia and maybe nitrogen.

As icy comets hit the Earth from space, they may also have added to our water supplies. Many thousands of tonnes of water fall onto Earth from space every year, even today.

When the boundaries of tectonic plates meet, forces build up which can cause the plates to buckle to become mountains, separate to form volcanoes or suddenly slip past each other to cause earthquakes. Although we can predict earthquakes to some extent by measuring the temperatures of rocks (which heat up before an earthquake), we can’t know exactly when the plates will move.

Markers placed across plate boundaries can be measured by GPS to detect movement. Infrared satellites measure the temperatures of rocks, which heat up before an earthquake, but prediction is still not as accurate as many scientists would like it to be.